The works of Ādi Śaṅkarācārya

Chāndogyopaniṣadbhāṣyam

Verse 23

अतो यान्यन्यानि वीर्यवन्ति कर्माणियथाग्नेर्मन्थनमाजे सरण दृढस्य धनुषआयमनमप्राणन्नपानन्स्तानि करोत्येतस्य हेतोर्व्यानमेवोद्गीथमुपासीत ॥ ५ ॥

In plain words

Therefore, whatever other strenuous tasks there are—such as kindling fire by friction, running in a race, or drawing a stiff bow—he performs them without exhalation or inhalation. For this very reason, one should meditate upon vyāna alone as the udgītha.

Close to the Sanskrit

Therefore, whatever other vigorous actions there are—such as the churning of fire, running in a race, the drawing of a sturdy bow—he performs those without exhaling and without inhaling. For this reason one should meditate upon vyāna itself as the udgītha.